The -76 is the first year IIRC in the 70's that's identifiable, so it can be a bit pricier than the early 70's instruments, but not by much. A couple of years ago I sold -71 LP Custom with Symor Duncans for 1900&#8364; which was a decent price for it over here. They were going between $1500 and $3000 back then in the US market area.

If we are talking about SG guitar, a Custom and/or Special with the Bixby type whammy, they can fetch a higher price than the standards. Mind You that the pickups of that era are nothing to write home about, but originality is the key for the top dollar.

I don't know a squat about the EB series as they're as rare as hens teeth over here.

In any case $6K sounds WAY overpriced, half of that maybe? In a different economy that is, now perhaps less.